Can't connect to one of my partner computers

I've been a very happy TV user for many years. I have four computers in my hope that are part of my partners. One of them is a HTPC connected to a projector, so I use TeamViewer when I want to work on this computer but don't want to pull down the screen and turn on the projector.

Today, when I wanted to connect to the HTPC from my MacBook I get this error message:


However, when I look at TV on the HTPC, in the bottom left corner there's a yellow dot that says "Incoming connection..." and nothing happens.

I have assigned the HTPC device to my account and both computers are signed in.

I then tried to connect from my HTPC to my MacBook and that worked without any problems.

Any ideas what is going on or how I can troubleshoot the problem further?

Thanks